Oxidation-resistant anodic protection coating and preparation method thereof

Abstract

The invention discloses an oxidation-resistant anodic protection coating and a preparation method thereof, and relates to the technical field of battery and / or electrolytic anodic protection coatings. The oxidation-resistant anodic protection coating comprises the following components in parts by mass: 5-15 parts of rare earth oxide, 10-25 parts of transition metal carbide, 2-4 parts of resin and 0.1-5 parts of an antioxidant. Through the compounding effect of rare earth oxide (such as lanthanum oxide) and transition metal carbide (such as tungsten carbide) and in combination with the oxygen free radical capturing capacity of rigid aromatic rings in the antioxidant, the physical barrier and chemical antioxidant synergistic effect of the coating is remarkably improved. Compared with a traditional single-component coating (such as a sodium silicate or aluminum oxide base), the system shows more lasting oxygen barrier capacity in a high-temperature and strong-oxidation environment. Mechanical support is enhanced through a cross-linked network of a resin matrix, and the steric effect and hydrogen-bond interaction of R1 groups (such as phenyl) in the antioxidant are combined, so that the structural stability of the coating at high temperature is improved, and meanwhile, the application scenarios of the coating in severe environments such as electrolysis and batteries are widened.

Description

Technical Field

[0001] The present invention relates to the technical field of battery and / or electrolytic anode protective coatings, and in particular to an oxidation-resistant anode protective coating and a preparation method thereof. Background Art

[0002] In the aluminum electrolysis industry, carbon anodes are core components of electrolytic cells, and their performance is directly related to production efficiency and cost. However, carbon anodes are prone to oxidation reactions in high-temperature and highly oxidizing electrolytic environments, resulting in accelerated consumption of anode carbon blocks, surface shedding, and the production of carbon slag. Anodic protection technologies often use a single coating or a simple mixture, which suffers from problems such as insufficient coating density, poor high-temperature stability, and an inability to self-heal. Although early silicate-based coatings can partially block oxygen, they are prone to failure due to thermal stress cracking; while alumina-based coatings are environmentally friendly, they have limited protection against mechanical impact and long-term high-temperature corrosion.

[0003] Currently, oxidation-resistant anodic protective coatings are based on a single material system. Early coatings mostly used single components such as alumina and sodium silicate. While mixtures of alumina, water, and sol can reduce anodic oxidation shedding, their coatings lack thickness and density, making them inadequate for long-term resistance to high-temperature oxidation. Sodium silicate-based antioxidants can form a protective shell, but asbestos poses an environmental risk, and the coatings are brittle and susceptible to mechanical damage from shelling. Functional deficiencies also prevent traditional coatings from self-healing. Once cracks or localized damage occur, oxidation rapidly spreads inward. Environmentally friendly alumina coatings can reduce carbon residue, but they are unable to repair microcracks at high temperatures, resulting in limited effectiveness in extending the anode cycle. Due to limitations in materials, processes, and functional design, traditional technologies are unable to meet the aluminum electrolysis industry's combined demands for long anode life, low cost, and environmental friendliness. Breakthroughs are needed through innovations in composite structures, self-healing mechanisms, and low-temperature curing processes. The development of an oxidation-resistant anodic protective coating that combines high oxygen barrier properties, self-healing capabilities, high-temperature resistance, and chemical stability is a key requirement for improving anode life and electrolysis efficiency. Summary of the Invention

[0004] The purpose of the present invention is to address the problems existing in the prior art and to provide an oxidation-resistant anode protective coating having high oxygen barrier properties, self-healing ability, high temperature resistance and chemical stability, and a preparation method thereof.

[0005] To achieve the above object, the technical solution adopted by the present invention is: an oxidation-resistant anode protective coating, comprising the following components in the following mass ratios: 5-15 parts of rare earth oxide, 10-25 parts of transition metal carbide, 2-4 parts of resin, and 0.1-5 parts of antioxidant;

[0006] The antioxidant has a structure shown in Formula 1:

[0007] Formula 1;

[0008] The R1 is selected from the group consisting of: methyl, ethyl, propyl, tert-butyl, phenyl, and methoxy.

[0009] Furthermore, the rare earth oxide is selected from at least one of lanthanum oxide, cerium oxide, and yttrium oxide.

[0010] Furthermore, the transition metal carbide is at least one of titanium carbide, tungsten carbide, and tantalum carbide.

[0011] Furthermore, the resin is selected from: epoxy resin and / or acrylate resin.

[0012] Furthermore, the antioxidant is selected from any one of the compounds shown in the following structures:

[0013] ;

[0014] ;

[0015] .

[0016] Furthermore, the synthesis method of the antioxidant is:

[0017] ;

[0018] Step 1: Raw materials 1 and 2 are synthesized through Suzuki coupling reaction to obtain intermediate 1;

[0019] Step 2: Intermediate 1 reacts with raw material 3 via Buchwald-Hartwig aromatic amination reaction to obtain antioxidant 6.

[0020] A method for preparing an oxidation-resistant anodic protective coating comprises the following steps:

[0021] S1. The rare earth oxide, transition metal carbide, resin and antioxidant are mixed, an organic solvent is added, and the mixture is stirred at a speed of 500-2000 rpm for 0.5-2 hours to obtain a uniform slurry;

[0022] S2. The uniform slurry is heated to 80-100° C., stirred for 2-3 hours, and cooled to room temperature to obtain an oxidation-resistant anode protective coating.

[0023] Furthermore, the oxidation-resistant anode protective coating is sprayed or brushed on the pre-treated metal substrate anode surface and cured at 80-100° C. for 0.5-4 hours to form an oxidation-resistant anode.

[0024] Furthermore, S1 and S2 are performed under a nitrogen atmosphere.

[0025] Furthermore, the wet film thickness formed by the coating is 20-50 μm, and the dry film thickness after curing is 15-40 μm.

[0026] Furthermore, an oxidation-resistant anode protective coating is used in the preparation of fuel cells, supercapacitors, organic flow batteries, water electrolysis, CO2 electrolysis, CO electrolysis, CO2 purification, heavy metal separation, electrically driven CO2 enrichment, lithium salt recovery, and as an electrolytic anode protective coating.

[0027] The antioxidant described in the present invention has a rigid aromatic ring skeleton. The conjugated π-electron system of the aromatic ring skeleton can capture oxygen free radicals, blocking the oxidation chain reaction. The steric effect of the R1 group inhibits the disentanglement of the molecular chain at high temperatures, while forming a hydrogen bond network with the hydroxyl groups on the surface of the rare earth oxide, enhancing the coating interface bonding strength. The rare earth oxide described in the present invention consumes active oxygen species through redox cycles; the transition metal carbide forms a physical oxygen barrier with its high hardness and low oxygen diffusion coefficient; the resin matrix provides mechanical support through a cross-linked network; and the antioxidant forms a "sacrifice-repair" dual mechanism with the rare earth oxide through dynamic sulfur bonds, preferentially oxidizing to form a dense oxide layer in the crack propagation path, achieving in-situ self-repair.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] 1. Synergistically enhanced antioxidant properties: Through the combined action of rare earth oxides (such as lanthanum oxide) and transition metal carbides (such as tungsten carbide), combined with the oxygen free radical capture ability of the rigid aromatic rings in the antioxidant, the coating's physical barrier and chemical antioxidant properties are enhanced. Compared to traditional single-component coatings (such as sodium silicate or aluminum oxide), this system exhibits more durable oxygen barrier properties in high-temperature and highly oxidizing environments.

[0030] 2. Dynamic self-healing capability: The dynamic sulfur bonds in the antioxidant form a "sacrificial-repair" mechanism with the rare earth oxide surface. When microcracks form in the coating due to thermal stress or mechanical impact, the antioxidant preferentially oxidizes to form a dense protective layer, blocking the oxidation pathway and enabling in-situ self-repair. This feature eliminates the problem of traditional coatings failing due to crack propagation, thereby extending the service life of the anode.

[0031] 3. Improved process adaptability and stability: A gradient heat treatment process (slow heating and cooling) combined with ion spraying technology optimizes stress distribution within the coating and interfacial bonding strength. The cross-linked network of the resin matrix enhances mechanical support, combined with the steric effect and hydrogen bonding of the R1 group (such as phenyl) in the antioxidant, improves the coating's structural stability at high temperatures and broadens its application in harsh environments such as electrolysis and batteries. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1The invention provides a method for synthesizing the antioxidant. DETAILED DESCRIPTION

[0033] The following will clearly and completely describe the technical solution of the present invention in conjunction with the accompanying drawings. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0034] Synthesis example 1

[0035] Synthesis of antioxidant 1:

[0036] ;

[0037] In the first step, under a nitrogen atmosphere, 20 g of raw material 1 and 28.03 g of raw material 2 were added to the reaction system in sequence, and 22.93 g of anhydrous potassium carbonate was added and dissolved in a mixed solution of toluene, ethanol, and water (volume ratio 2: 1: 1). The nitrogen was replaced twice. Under nitrogen protection, 95.88 g of tetrakis(triphenylphosphine)palladium was added to the phase system, and the nitrogen was replaced twice. The reaction was heated to 75 ° C. and refluxed for 10 hours. The heating was turned off, cooled to room temperature, and allowed to stand for separation. The aqueous phase was extracted twice with ethyl acetate, the organic phases were combined, washed three times with water, spin-dried, and chromatographed on a silica gel column using a mixture of petroleum ether and ethyl acetate as an eluent to obtain 26.18 g of intermediate 1.

[0038] In the second step, under nitrogen protection, 26.18 g of intermediate 1 and 22.83 g of raw material 3 were added to the reaction system in sequence and dissolved in toluene solution, 5.94 g of sodium tert-butoxide, 56.61 g of tris(dibenzylideneacetone)dipalladium, and 12.51 g of tri-tert-butyl phosphine were added, stirred evenly, heated to 120 ° C, and refluxed for 12 hours; after the reaction was completed, the temperature was slightly lowered, filtered using diatomaceous earth, the filtrate was cooled to room temperature, washed three times with water, the organic phase was retained, and the aqueous phase was extracted with ethyl acetate; after the organic phases were combined, dried with anhydrous magnesium sulfate, filtered, and spin-dried to obtain 33.44 g of antioxidant 1.

[0039] Product structure identification:

[0040] MS [MS+H] of intermediate 1 + :424;

[0041] MS of antioxidant 1 [MS+H] + :699.

[0042] Synthesis Example 2-Synthesis Example 6

[0043] In Synthesis Examples 2 to 6, antioxidants 2 to 6 were synthesized in sequence, referring to the synthesis method of Synthesis Example 1, except that raw material 1 was replaced, and the other conditions remained the same as those of Synthesis Example 1. Specific structures of raw material 1, antioxidants 2 to 6, MS [MS + H] + See Table 1 for data.

[0044] Table 1. Structure of raw material 1, structure of antioxidant 2-antioxidant 6, MS [MS+H] of Synthesis Examples 2-6 + data.

[0045] .

[0046] .

[0047] Example 1

[0048] An oxidation-resistant anode protective coating base and an oxidation-resistant anode

[0049] 1. Raw material ratio: 10 parts of rare earth oxide (lanthanum oxide), 18 parts of transition metal carbide (tungsten carbide), 3 parts of resin (epoxy resin), 0.25 parts of antioxidant (antioxidant 1 prepared in Synthesis Example 1);

[0050] 2. Preparation method:

[0051] The aluminum electrolytic anode substrate was sandblasted to a surface roughness of Ra 2.5 μm, then ultrasonically cleaned with acetone for 20 minutes and dried at 60°C for 30 minutes. A mixture of rare earth oxides, transition metal carbides, resin, an antioxidant, and an organic solvent was placed in a nitrogen atmosphere in a reactor and stirred at 300 rpm for 1.5 hours to produce a uniform slurry. The slurry was sprayed onto the pretreated substrate surface with a wet film thickness of 35 μm. The coated substrate was cured at 90°C in a nitrogen atmosphere for 2 hours to form an oxidation-resistant anode with a dry film thickness of 28 μm.

[0052] Example 2-Example 6

[0053] An oxidation-resistant anode protective coating base and an oxidation-resistant anode are prepared by referring to the preparation method of Example 1, wherein the slow-release stabilizer is replaced with the oxidation-resistant agent 2 to the oxidation-resistant agent 6 synthesized in Synthesis Example 2 to Synthesis Example 6 in sequence, and the rest remains the same as Example 1.

[0054] Comparative Example 1

[0055] The preparation of an oxidation-resistant anode protective coating base and an oxidation-resistant anode is similar to that of Example 1 except that the oxidation-resistant agent is not added.

[0056] Comparative Example 2

[0057] An oxidation-resistant anode protective coating base and an oxidation-resistant anode are prepared by referring to the preparation method of Example 1, except that the mass ratio of the rare earth oxide is replaced with 20 parts, and the rest remains the same as Example 1.

[0058] Comparative Example 3

[0059] An oxidation-resistant anode protective coating base and an oxidation-resistant anode are prepared by referring to the preparation method of Example 1, except that the mass ratio of the resin is replaced with 9 parts, and the rest remains the same as Example 1.

[0060] Performance testing:

[0061] The current efficiency and enhanced electrolysis life of an oxidation-resistant anode prepared in the examples and comparative examples were measured, wherein the test temperature for the current efficiency (referring to the analysis method for the effective chlorine concentration in GB12176-90) was 10°C, the reference electrode was a saturated calomel electrode, and the applied current density was 0.5A / m 2 The enhanced electrolysis life test was carried out in seawater at a temperature of 10°C and a current density of 5000A / m 2 The measurement results are shown in Table 2.

[0062] Table 2. Current efficiency and enhanced electrolysis life data of an oxidation-resistant anode prepared in Examples and Comparative Examples.

[0063]

[0064] The examples significantly outperformed the comparative examples in terms of current efficiency and enhanced electrolysis lifespan, with current efficiencies exceeding 95% and lifespans exceeding 180 hours, effectively validating the key role of the antioxidant. Comparative Example 1, which lacked an antioxidant, had the lowest current efficiency and lifespan, indicating that the lack of a self-repair mechanism facilitates rapid expansion of oxidation cracks. In Comparative Example 2, excessive rare earth elements caused lanthanum oxide agglomeration, reducing coating density and resulting in a 40% reduction in lifespan compared to Example 1. In Comparative Example 3, excessive resin accelerated pyrolysis and oxygen permeation, resulting in a 3.6% reduction in current efficiency.

[0065] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. An oxidation-resistant anodic protective coating, characterized in that: The invention comprises the following components in the following mass ratios: 5-15 parts of rare earth oxide, 10-25 parts of transition metal carbide, 2-4 parts of resin, and 0.1-5 parts of antioxidant; The antioxidant has a structure shown in Formula 1: Formula 1; The R1 is selected from the group consisting of: methyl, ethyl, propyl, tert-butyl, phenyl, and methoxy.

2. The oxidation-resistant anodic protective coating according to claim 1, characterized in that: The rare earth oxide is selected from at least one of lanthanum oxide, cerium oxide, and yttrium oxide.

3. The oxidation-resistant anodic protective coating according to claim 1, characterized in that: The transition metal carbide is at least one of titanium carbide, tungsten carbide and tantalum carbide.

4. The oxidation-resistant anodic protective coating according to claim 1, characterized in that: The resin is selected from: epoxy resin and / or acrylate resin.

5. The oxidation-resistant anodic protective coating according to claim 1, characterized in that: The antioxidant is selected from any one of the compounds shown in the following structures: ； ； 。 6. A method for preparing an oxidation-resistant anodic protective coating according to any one of claims 1 to 5, characterized in that: The following steps are involved: S1. The rare earth oxide, transition metal carbide, resin and antioxidant are mixed, an organic solvent is added, and the mixture is stirred at a speed of 500-2000 rpm for 0.5-2 hours to obtain a uniform slurry; S2. The uniform slurry is heated to 80-100° C., stirred for 2-3 hours, and cooled to room temperature to obtain an oxidation-resistant anode protective coating.

7. The method for preparing an oxidation-resistant anodic protective coating according to claim 6, characterized in that: The oxidation-resistant anode protective coating is sprayed or brushed on the pretreated metal substrate anode surface to form a wet film, and is cured at 80-100° C. for 0.5-4 hours to form a dry film, thereby forming an oxidation-resistant anode.

8. The method for preparing an oxidation-resistant anodic protective coating according to claim 6, characterized in that: The S1 and S2 were performed under a nitrogen atmosphere.

9. The method for preparing an oxidation-resistant anodic protective coating according to claim 7, characterized in that: The wet film thickness is 20-50 μm, and the dry film thickness after curing is 15-40 μm.

10. An application of an oxidation-resistant anode protective coating according to any one of claims 1 to 5 in the preparation of fuel cells, supercapacitors, organic flow batteries, water electrolysis, CO2 electrolysis, CO electrolysis, CO2 purification, heavy metal separation, electrically driven CO2 enrichment, lithium salt recovery, and as an electrolytic anode protective coating.

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